This is a nice tidy and boxed example of Charpentier’s Calculimetre which was patented in France in 1882. Designed by G. Charpentier this pocket slide rule is the same diameter as a pocket watch and has a nickel plated body with a rotating inner brass disk. Despite its simplicity this was a versatile little thing being able to do logarithms, sines, tangents and square roots. It appears to have sold well around the globe under various distributors and iterations even up to the early 1930s. This classic French example is marked ’28’ just underneath the makers name which may relate to the 28th edition which came out in 1897.
It is offered in very good untouched original condition and rotates fine. The cloth hinge on the back of the box has been renewed.
Diameter of slide rule: 6cm
